what is "nits" (brightness)? how to calculate?

i think my battery drains too fast but i'm not really sure, i want to test my battery life so i checked how asus tested battery life

Battery life tested under power saving mode, playing 720p video playback, Brightness:60nits, default volume with headphones.

(They claim the battery 10 hours without dock)
but i'm not sure what does "60 nits" mean? i heard the tf300 "has" 350 nits, so 60/350= around 17%. but if you set your brightness to 17% you can't really see anything. so i get confused.

and it's funny that's they tested the battery under power saving mode, "default volume" with headphones, i mean it sounds like they want to save the battery power as much as possible and to give us the number 10 hours. what if they tested in balanced mode (which is the default mode) with speaker not headphones? and again, i don't know how many % are 60 nits?

Could you change your settings so we can be sure what Tablet you have, your profile says "none". 10 Hours is in power saving mode. Less in other modes. Simple, they advertise maximum life attainable, like other tablet makers. Depending on the apps you are using, items like live wallpapers, background processes and the like you will most likely get less. Be sure to read the Batttery Use link below.

Nits relates to brightness, TF300 max is 350. The TF700 max is 600. This makes it very bright for use outdoors for instance. How to convert brightness level to nits ? I don't know myself.

Could you change your settings so we can be sure what Tablet you have, your profile says "none". 10 Hours is in power saving mode. Less in other modes. Simple, they advertise maximum life attainable, like other tablet makers. Depending on the apps you are using, items like live wallpapers, background processes and the like you will most likely get less. Be sure to read the Batttery Use link below.

Nits relates to brightness, TF300 max is 350. The TF700 max is 600. This makes it very bright for use outdoors for instance. How to convert brightness level to nits ? I don't know myself.

Thanks for reminding. I changed it. My tablet is TF300T

Originally Posted by Frederuco

Why is it tested this way?

Because that is how the iPad started its benchmark. Since that is how the iPad has been tested, they wanted to give a fair battery life comparison.

Also, 60 nits is just about or just slightly above minimum brightness.

It is also tested with GPS, WiFi and Bluetooth off.

so it's like 17% or even lower like i guessed? how can they watch video in that brightness setting? maybe in dark room lol.

so it's like 17% or even lower like i guessed? how can they watch video in that brightness setting? maybe in dark room lol.

but i don't even know what "candela per suare metre" is.
well i guess there's no way to convert nits to brighness percent.

It is hard to say because minimum brightness is not 0 nits, there is still some brightness. I am guessing it is just about the very bottom of the slider. I use my tablet at this brightness most of the time unless I am in a VERY bright room, or where sun glare is an issue. But, I also keep my phone at a low brightness and it drives my wife crazy every time she picks it up. Her iPhone and iPad are probably 80% brightness or higher all of the time.

As far as actually converting it, you would need to have a light meter to measure brightness to know exactly where 60 nits is. It will vary from device to device based on variance in backlight from one unit to another on the exact percentage.

As an old TV equipment design engineer I can explain the Nit - but you don't really need to understand it - just compare the figures on the spec to other devices.
The Nit is an old word that they seem to have dug up and dusted off. It is identical to the Candela per square metre, which is NOT a measure of brightness but is the SI unit of LUMINANCE. Brightness is the commonly used word for LUMINOSITY or perceived intensity. You can measure luminance but brightness is subjective. That means it depends on the viewer, the ambient conditions and the history - if you stare at something bright you will be desensitised and the brightness of something else will be lower, that's what happens when you take your device outside and it seems dimmer. The luminance is the same but the luminosity is less because the ambient light is more intense. Unfortunately, the human eye is non linear and the brightness is different for different wavelengths (hues) and a light that is twice as intense is not twice as bright. So, the transformer with 650 Nits of luminance isn't about twice as "bright" as one with only 350 Nits; there is much less perceived difference. Bit simplified but it may help understanding the numbers.
Kev

Ooops! just read the original post on this thread. 60 Nits is not 60/350 of total brightness. It is much more - see what I said above.
Just set your display to a fairly low but viewable brightness.
Kev